1. Field of the Invention
The present invention relates to PoC (Push To Talk over Cellular) and extended-PoC communication system, and in particular to a method and a server which enable insertion of advertisements.
2. Description of the Related Art
PoC communication is communication using SIP (RFC 3216), which is an Internet protocol, and it enables communication among groups using a mobile phone network. The PoC communication is disclosed, for example, in Japanese Patent Laid-Open No. 2005-260973.
In a PoC communication system, there are multiple terminals connected to a PoC server to transmit and receive voice via half-duplex communication.
When transmission is performed, the terminal first requests the right to speak from the PoC server. The PoC server determines whether or not to approve the right to speak in a separately determined procedure. If the right to speak is to be approved, then it is issued to the terminal. Upon receiving the right to speak, the terminal transmits voice speech to the PoC server. To such terminals that do not have the right to speak, speech is transmitted from the PoC server. In this way, voice communication among multiple terminals is realized via half-duplex communication.
PoC can realize voice communication among two or more terminals by effectively utilizing a relatively narrow communication band, and it has attracted a lot of attention recently. International standardization of PoC is being promoted, and it is expected that PoC will become wide spread in the future. The result of PoC standardization activities by OMA (Open Mobile Alliance) is provided on the site: http://www.openmobilealliance.org/release_program/poc-v1—0.html.
A lot of services and content are provided free on the Web. For most of them, a business model called an advertisement model is adopted. This is a model for acquiring advertisement revenue by displaying advertisement on a part of the display area of a browser or by inserting advertisement copy in an e-mail, and there are various variations of this model.
However, this kind of advertisement model is hardly used in voice communication including telephone communication. Only a model in which a voice advertisement is inserted before the start of conversation has been implemented.
This is because determination of the position or the timing of inserting advertisement after start of the conversation is very difficult. Insertion after start of conversation may often interfere with the conversation itself, and as a result, the user feels uncomfortable, and the advertisement effect is negated. In the case of a model in which the advertisement is inserted at the beginning of a conversation, a problem occurs in that, when the conversation time becomes long, there will be a large gap between the benefit that the ad will created and the amount of advertisement.
An advertisement model is often effective for promoting of a service. However, in voice communication, there is a problem that the advertisement model has not been effectively utilized.